During a surgical procedure, for example a hip arthroplasty, a surgeon may be provided with a set of differently sized prostheses from which the most suitable prosthesis may be chosen in accordance with the anatomy of the patient. A set of surgical instruments, for example trial implants, may be used whilst performing the surgical procedure to assess which size of prosthesis best matches the patient's anatomy. Each trial implant may have differently sized features that correspond to the differently sized prostheses. It is desirable, therefore, during surgery to be able to easily match the prosthesis and the corresponding trial implant.
It is known to colour-code components using anodisation techniques to help identify prostheses and tools. Such anodisation techniques typically involve immersing the component in acid to remove an oxide layer, and subsequently performing the anodisation by submerging the component an electrolyte fluid. However, it is very difficult to selectively anodise a specific surface of the component using such known techniques. Even if the component is partially immersed in the fluid to treat only a specific portion of the component, the surface tension of the fluid results in unwanted treatment of the component where the component breaks the surface of the fluid. It is desirable, therefore to selectively anodise only the specific surface of the component to avoid introducing any unwanted chemicals onto other surfaces of the component, for example surfaces of a prosthesis designed to engage a bone and/or another prosthetic component, and to avoid any unsightly anodisation gradients between treated surfaces and the surfaces adjoining the treated surfaces.